Model:
public class Person : IValidatableObject
{
public Address ResidentialAddress { get; set; }
public Address PostalAddress { get; set; }
}
public class Address
{
public string Address1 { get; set; }
}
in Model:
public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
{
if (string.IsNullOrWhiteSpace(PostalAddress.Address1))
{
yield return
new ValidationResult("Postal address is required",
new[] { nameof(PostalAddress.Address1) });
}
}
View: (A partial view for address inside the View for Person)
#Html.ValidationMessageFor(m => m.Address1)
In the html this comes out with the name PostalAddress.Address1 and the id PostalAddress_Address1
Unfortunately nameof(PostalAddress.Address1) just returns Address1.
I have tried replacing it with PostalAddress.Address1 and PostalAddress_Address1 and can't get the error to show up.
What's the secret?
I think #MikeDebela is right in the comment below your answer. Your model needs to implement IValidatableObject if you're going to use custom model validation like that. However, that's not your only problem.
First, is there a particular reason you're not just relying on the [Required] attribute for this? Custom model validation is a bit of a waste for something this simple. If the issue is that this is your actual entity class, and you don't want the Address1 column non-nullable at the database-level, well, that's what view models are for. Use them. You can make the property required on just your view model. As a best practice, you should never utilize your entity classes directly to post to.
Also, you're never newing up PostalAddress. When the model binder does its thing on post, if no properties of a related class are posted, it leaves the value of the that related class as null. Then, any related classes that are null, are also not validated. As a result, if the only property is Address1 and you don't post Address1, then PostalAddress is null, and no property on it, specifically, Address1, will participate in validation.
Related
I have an object that I would like to display in a Details view. The object has a bunch of properties that the view needs.
The object also has parents and grandparents, which I need to display in the view.
What I have for my object viewModel is:
public class ObjectViewModel
{
// Used when creating a new object under a parent object
[HiddenInput(DisplayValue = false)]
public int? ParentObjectId { get; set; }
[Required]
public Object Object { get; set; }
// Info that only the view needs, which is defined in the Controller based on some logic
public string ActiveTitle { get; set; }
// A bre
public IList<Object> ParentObjects { get; set; }
}
I then use this in my Detail controller method:
public ActionResult Detail(int objectId)
{
// TODO: Make this a service call
var object = _db.Objects.FirstOrDefault(s => s.ObjectId == objectId);
if (object == null)
{
return View("Error");
}
var model = new SetViewModel() {
ActiveTitle = object.Name,
Object = object,
ParentObjectId = object.ParentObject.ObjectId,
ParentObjects = _objectService.GetParentObjects(set.ParentObject)
};
return View(model);
}
Does this look right? Or should I be pulling the required fields from the Object model into the viewModel, and not the objects themselves?
To have an object type in your view model is super vague and your code would be hard to support if you are not the original programmer. I would Add the class type to the actual model or use generics to specify the class type as shown below:
public class ObjectViewModel<T>
{
// Used when creating a new object under a parent object
[HiddenInput(DisplayValue = false)]
public int? ParentObjectId { get; set; }
[Required]
public T Object { get; set; }
// Info that only the view needs, which is defined in the Controller based on some logic
public string ActiveTitle { get; set; }
// A bre
public IList<T> ParentObjects { get; set; }
}
Either option will work, and you will often have a mixture of both techniques in a given application.
The key idea is that your view model should contain what the view needs in order to display the data to the user.
If your view merely displays the individual, primitive fields in simply controls, e.g. a series of labels or textbox controls, then your view model should probably specify only the fields, and not the parent object.
However, it's very possible for your view to include a templated or custom control that "knows how" to display a complex object in its entirety. In that case, your view model would need to include the entire object. (In practice I find myself doing this much more often in WPF than ASP-MVC but I've done both).
It looks like the answer will be contextual. Many teams using layered architectures might adopt architectural conventions whereby layers below X should not be referenced directly by your views, and a data access class might be a likely candidate for such a restriction. In your case, it does look like you will be binding your view's structure to the structure directly to your database schema (assuming, since you're using "_db"), which might be considered unreasonably tight coupling.
Also, I'm assuming you're using "object" to represent "any general thing" rather than literally a System.Object, since your objects appear to have an ObjectId property in your lambda expression.
I would like to use the built-in validation features as far as possible. I would also like to use the same model for CRUD methods.
However, as a drop down list cannot be done using the standard pattern, I have to validate it manually. In the post back method, I would like to just validate the drop down list and add this result to ModelState so that I don't have to validate all the other parameters which are done with Data Annotation. Is it possible to achieve this?
I may be mistaken about the drop down list, but from what I read, the Html object name for a drop down list cannot be the same as the property in the Model in order for the selected value to be set correctly. Is it still possible to use Data Annotation with this workaround?
Thanks.
You can use the addModelError
ModelState.AddModelError(key,message)
when you use that, it will invalidate the ModelState so isValid will return false.
Update
after seeing the comment to #Pieter's answer
If you want to exclude an element from affecting the isValid() result, you can use the ModelState.Remove(field) method before calling isValid().
Another option is to inherit IValidatableObject in your model. Implement its Validate method and you can leave all other validation in place and write whatever code you want in this method. Note: you return an empty IEnumerable<ValidationResult> to indicate there were no errors.
public class Class1 : IValidatableObject
{
public int val1 { get; set; }
public int val2 { get; set; }
public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
{
var errors = new List<ValidationResult>();
if (val1 < 0)
{
errors.Add(new ValidationResult("val1 can't be negative", new List<string> { "val2" }));
}
if (val2 < 0)
{
errors.Add(new ValidationResult("val2 can't be negative", new List<string> { "val2" }));
}
return errors;
}
}
EDIT: After re-reading the question I don't think this applicable to this case, but I'm leaving the answer here in case it helps someone else.
You cannot manually set the ModelState.IsValid property but you can add messages to the ModelState that will ensure that the IsValid is false.
ModelState.AddModelError();
yes, you can achieve this (also you will use the same model for CRUD methods) :
Example MODEL
public class User
{
public virtual int Id{ get; set; }
public virtual Role Role { get; set; }
}
public class Role
{
[Required(ErrorMessage = "Id Required.")]
public virtual int Id { get; set; }
[Required(ErrorMessage = "Name Required.")]
public virtual string Name { get; set; }
}
Example VIEW with validation on the dropdownlist
#Html.DropDownListFor(m => m.Role.Id, (SelectList)ViewBag.gRoles, "-- Select --")
#Html.ValidationMessageFor(m => m.Role.Id)
CONTROLLER: clearing the required (but not needed here) fields
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Creedit(User x)
{
x.Role = db.RoseSet.Find(x.Role.Id);
if (x.Role != null)
{
ModelState["Role.Name"].Errors.Clear();
}
if (ModelState.IsValid)
{
// proceed
}
else
{
// return validation error
}
}
Might be more recent methods, since this is an old post, but this might help future readers.
One can set a field to valid with this two methods:
ModelState.ClearValidationState("Password");
ModelState.MarkFieldValid("Password");
Need to use both because the second one without the first one it gives an error stating that the state is already marked.
To set a field to invalid, just use ModelState.AddModelError() method as already referred.
How do you validate a class using Validation attributes when validating strongly typed view models.
Suppose you have a view model like so:
[PropertiesMustMatch("Admin.Password", "Admin.ConfirmPassword")]
public class AdminsEditViewModel
{
public AdminsEditViewModel()
{
this.Admin = new Admin(); // this is an Admin class
}
public IEnumerable<SelectListItem> SelectAdminsInGroup { get; set; }
public IEnumerable<SelectListItem> SelectAdminsNotInGroup { get; set; }
public Admin Admin { get; set; }
}
I get null exception when on this line of PropertiesMustMatchAttribute
object originalValue = properties.Find(OriginalProperty, true /* ignoreCase */).GetValue(value);
since Password field is a property of Admin class and NOT AdminsEditViewModel. How do I make it so that it will go so many levels deep until it does find property of Admin in the ViewModel AdminsEditViewModel?
thanks
You need to modify the PropertiesMustMatchAttribute class to parse the property name and search deeply.
This attribute is not part of the framework; it's included in the default MVC template (in AccountModels.cs)
You can therefore modify it to suit your needs.
Specifically, you would call name.Split('.'), then loop through splitted names and get the property values.
It would look something like
object GetValue(object obj, string properties) {
foreach(strong prop in properties)
obj = TypeDescriptor.GetProperties(obj)
.Find(prop, ignoreCase: true)
.GetValue(obj);
}
return obj;
}
I just wondered how people were approaching this situation. It's something that seems like a weak point in my usage of MVC with ORMs (NHibernate in this case)...
Say you have a fine-grained and complicated entity in your model. You will likely have an admin page to manage objects of this type. If the entity is complicated, it is unlikely that you will be modifying the whole entity in one form. You still need to pass the relevant properties to the view, and incorporate changes to those properties in the model when the view returns them.
What does anyone do in this situation?
Create a view model which is (or contains) a subset of the entities properties. Pass this to and from the view. In 'edit' action method in controller, get the object from repository, go though all the properies in the ViewModel and apply them to the Model object (model.a = viewmodel.a, modelb = viewmodel.b). This seems the obvious sensible route, but generates a lot of tedious plumbing code. Also this complicates validation a bit.
Something else?
I've looked briefly at automapper - but this doesn't seem to fit the bill exactly, maybe I'm wrong?
Thanks.
This sounds like the perfect scenario for automapper. You create a view model class which contains a subset of the fields or your real model, and you let AutoMapper take care extraccting values from the domain model object into your view model object. What issues are you having with this approach?
Consider this example:
Here is your domain model and your view model
public class Person
{
public string FirstName
{ get; set; }
public string LastName
{ get; set; }
public string HomeNumber
{ get; set; }
public string Address1
{ get; set; }
public string Address2
{ get; set; }
}
public class PersonViewModel
{
public string FirstName
{ get; set; }
public string LastName
{ get; set; }
public string HomeNumber
{ get; set; }
}
Here is your mapping, you have to create a mapping in both directions from dm->vm and vm->dm.
From what I've seen when using Automapper is that if you map from object A to B and B has a property which A doesn't have, it will be reset. So when I create the map I direct it to ignore those missing properties. I'm not a Automapper expert so I may be using it wrong.
Mapping
Mapper.CreateMap<Person, PersonViewModel>();
// Automapper will reset values in dest which don't exist in source, so be sure to ignore them!
Mapper.CreateMap<PersonViewModel, Person>()
.ForMember(dest => dest.HomeNumber, opt => opt.Ignore());
Finally usage:
Person p = new Person()
{
FirstName = "First",
LastName = "Last",
Address1 = "add 1",
Address2 = "add 2"
};
PersonViewModel pvm = Mapper.Map<Person, PersonViewModel>(p);
// Map to a new person
Person p2 = Mapper.Map<PersonViewModel, Person>(pvm);
// Map to the existing person just to update it
Person p3 = new Person()
{
HomeNumber = "numberHere"
};
// This will update p3
Mapper.Map<PersonViewModel, Person>(pvm, p3);
Because of the exclusion, this is obviously less than ideal, but much better than manually doing the whole thing.
Have your view model map one-to-one with your domain model.
Specify Model as argument for the routeValues as below. This means your view model will be initialized with the values from the domain model. Only the sub set of fields in the form will be overwritten in the resulting personViewData.
Update View:
#model ViewModel.PersonView
#using (Html.BeginForm("Update", "Profile", Model, FormMethod.Post))
{
...Put your sub set of the PersonView fields here
}
ProfileController:
public ActionResult Update(string userName)
{
Person person = _unitOfWork.Person.Get().Where(p => p.UserName == userName).FirstOrDefault();
PersonView personView = new PersonView();
Mapper.Map(person, personView);
return View(personView);
}
[HttpPost]
public ActionResult Update(PersonView personViewData)
{
Person person = _unitOfWork.Person.Get().Where(p => p.UserName == personViewData.UserName).FirstOrDefault();
Mapper.Map(personViewData, person);
_unitOfWork.Person.Update(person);
_unitOfWork.Save();
return Json(new { saved = true, status = "" });
}
Why don't you use TryUpdateModel with the form collection.
If your view is editing a person
public class Person
{
public string ID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Email { get; set; }
public string Address { get; set; }
}
And your view is only editing first name and last name, you can do this:
public ActionResult Action(FormCollection form)
{
Person personToUpdate = Repository.GetPerson(form["ID"]);
TryUpdateModel<Person>(personToUpdate, form);
Repository.Update(personToUpdate)
return View();
}
That will only update Person with the items that a part of the form collection. If you don't want a field updated, don't submit it with the form.
What if you have full model but each page uses and updates only the required part? Then you update the business model using complete view data at the last page.
I use a similar approach to yours (in my case Entity Framework) with Entity -> ViewModel -> View but only on views with "complex" entities that have either 1:M or M:M relationships. In most cases I took the low road and went for Entity->View when I have a simple entity.
My ViewModel is defined as Entity+supporting properties: SelectList or MultiSelectList and either a string or List<string>. I'll also use a ViewModel for instances where I have properties I need for the view but may not necessarily need in the entity (database).
Http Get controller methods are straightforward ActionResults with return View(repository.FetchNewViewModel()) for Create or repository.FetchModelById(id) for Edit. In both instances I'm initializing my entities before passing them to the view.
Create([Bind(Exclude = "Entity.EntityId")] ViewModel model) and Edit(ViewModel model) are the Http Post controller methods of Create and Edit. My Edit view has a hidden input field for EntityId to pass it back and forth.
By the time the Http Post method has the viewmodel, I lose all Entity.Relation and ViewModel.(Multi)SelectList values. I have to rebuild the object if I want my view to display properly:
`
try
{
var tags = model.TagIds; // List<string> or <int> depending on your Id type
if (model.TagsList == null) // It will be
{
model.TagsList = _repository.FetchSelectedTags(tags); // Build a new SelectList
}
if (!ModelState.IsValid)
{
return View(model);
}
_repository.Add(model.Article, tags); // or Save() for Edit
}
catch
{
return View(model); // Generally means something screwed in the repository class
}
return RedirectToAction("Index");
`
There is maybe 30% of my entity base using a ViewModel so I definitely only use it as needed. If you have complex views and model data in most instances you can probably break it down to smaller views.
Right now i´m working on a large project using S#arp Architecture and im also using the approach:
Model -> ViewModel -> Model
I use the ViewModel for the Binding part and Validations, the other approach is to use the Model Directly (with tryUpdateModel / UpdateModel which we used during the prototype develop) but for complex scenarios we end up handling special situation like SelectLists/Checkbox/Projections/HMAC Validations in a little ViewModel anyway and using a lot of Request.Form["key"] =( , the other drawback is handling the errors situations where you want to repopulate the form with the user input, i found it a little more complicated using the Model directly (using a ViewModel we take a lot of advantage of ModelState attempted value, saving us a couple of trips to the DB, anyone who have faced this scenario will know what i mean).
This approach is a bit time consuming, just like you said, you end up matching properties, but in my opinion is the way to go for complex forms.
It worth mentioning that we just use ViewModels for the Create/Edit scenarios, for almost everything else we use directly the model.
I have not use autommapers so far, but definitely i ll give it a try.
Does it make sense create an object that contains only those properties that the user will input on the webpage, use that for binding in the controller, and then map to the full Entity Object? Or should you just use the entity object, and use Include and Exclude to make restrictions on what gets bound on input?
I have come to like the idea of using interfaces to segregate which properties should be included when the object is updated.
For example:
To create and update an person object:
interface ICreatePerson
{
string Name { get; set; }
string Sex { get; set; }
int Age { get; set; }
}
interface IUpdatePerson
{
string Name { get; set; }
}
class Person : ICreatePerson, IUpdatePerson
{
public int Id { get; }
public string Name { get; set; }
public string Sex { get; set; }
public int Age { get; set; }
}
Then, when binding model, just use the appropriate interface as the type and it will only update the name property.
Here is an example controller method:
public ActionResult Edit(int id, FormCollection collection)
{
// Get orig person from db
var person = this.personService.Get(id);
try
{
// Update person from web form
UpdateModel<IUpdatePerson>(person);
// Save person to db
this.personService.Update(person);
return RedirectToAction("Index");
}
catch
{
ModelState.AddModelErrors((person.GetRuleViolations());
return View(person);
}
}
See this article (and the comments) for a very good discussion of the options.
I recommend using a separate presentation model type in most cases. Aside from the issue of binding (which is important, but there are other ways around this issue), I think that there are other reasons why using presentation model types is a good idea:
Presentation Models allow "view-first" development. Create a view and a presentation model at the same time. Get your user representative to give you feedback on the view. Iterate until you're both happy. Finally, solve the problem of mapping this back to the "real" model.
Presentation Models remove dependencies that the "real" model might have, allowing easier unit testing of controllers.
Presentation Models will have the same "shape" as the view itself. So you don't have to write code in the view to deal with navigating into "detail objects" and the like.
Some models cannot be used in an action result. For example, an object graph which contains cycles cannot be serialized to JSON.